Ferrocene-Carbohydrate Conjugates as Electrochemical Probes for Molecular Recognition Studies

We report two methods that have allowed the attachment of glu- cose, mannose and lactose to one or both of the cyclopentadienyl rings of ferrocene. The resulting ferrocene-car- bohydrate conjugates were synthesised by the reaction of thioglycosides with ferrocenemethanol and 1,1'-ferrocene- dimethanol in acidic media. A second method based on the regiospecific cop- per(I)-catalysed cycloaddition of prop- argyl glycoside, azidomethyl and bis- Arocene as well as azi- doethyl glycoside and ethynylferrocene was also used and led to the synthesis of 1,2,3-triazole-containing glycoconju- gates. The electrochemical behaviour of the synthesised glycoconjugates was investigated. In addition, their binding interactions with b-cyclodextrin were studied by means of NMR spectrosco- py, isothermal titration calorimetry, and cyclic and differential pulse vol- tammetric experiments. These tech- niques allowed the determination of the thermodynamic parameters of the complexes, the stability constants for the complexes formed with both the neutral and the oxidised states of the ferrocenyl glycoconjugates, the mode of inclusion and the diffusion coeffi- cients for both the glycoconjugates and the complexes.